Weight Transferring Tow Dolly

ABSTRACT

My weight transferring tow dolly is releasably attachable to a receiver hitch of a towing vehicle such as a pickup truck and generally provides a dolly frame formed of plural structurally interconnected box beams having a height adjustable suspension carrying an axle with wheels and tires at opposing end portions, and a support frame to partially support the weight of a carried load and to move the center of gravity of a loaded towing vehicle forwardly to increase the stability of the towing vehicle.

RELATED APPLICATIONS

There are no prior filed patent applications related hereto heretoforefiled in the United States, nor in any foreign country.

FIELD OF INVENTION

This invention relates to land vehicles, and more particularly to atowable weight transferring dolly.

BACKGROUND OF THE INVENTION

Pickup trucks are a popular style of motor vehicle and are no longerused solely for carrying cargo and loads, but also for general transportand commuting. The popularity of pickup trucks has steadily increasedover the recent years. Pickup trucks have an occupant compartment (the“cab”) at a somewhat forward end portion that historically has had twodoors and a single bench seat for two and perhaps three passengers, anda rearward cargo bed that was commonly 8 feet in length. More recently,pickup trucks having a “crew cab” which is characterized by having 4doors and a rear seat have become increasingly popular because theyprovide a vehicle capable of transporting four or more adults as well ascargo in the truck bed.

Unfortunately, the addition of two additional doors and a back seat hasnecessitated that the overall length of the pickup truck be increased.Although the addition of the additional doors and a backseat has been ahuge benefit, and made pickup trucks increasing popular and moreversatile, the increased length has decreased the maneuverability, andconvenience of pickup trucks, because the great length makes suchvehicles difficult to park and maneuver.

In an effort to resolve the decrease in maneuverability, and thedifficulty in parking, manufacturers have resorted to promoting, and theconsuming public has generally accepted such four-door pickup truckshaving a shorter six-foot cargo bed rather than the standard longereight-foot cargo bed. Because owners are more commonly using pickuptrucks as a primary mode of transportation and for commuting, thereduced length of the cargo bed has not been a significant detriment.When an operator desires to transport a larger or longer item within thecargo bed, the operator may “lower” the bed tailgate and allow thelonger item to extend rearwardly beyond the rearward end of the tailgateand the pickup truck bed. With some limitations, traffic laws andregulations permit cargo items to extend rearwardly beyond the rearwardend of vehicle, so long as the protruding item does not extend too far,is properly secured, and a visible “warning flag” is attached to therearward most end of the item so that it is clearly visible to otherdrivers and vehicle operators.

Although allowing the cargo to extend beyond the lowered tailgate hasresolved some problems associated with the smaller 6 foot bed,difficulty continues when the item being transported in the bed islonger than the six-foot bed and is heavy toward a rearward end portion.In such instances, the cargo may change the center of gravity of thepickup truck which reduces the maneuverability and the stability of thepickup truck on the roadway because so much weight is carried rearwardof pickup truck's rear tires. Such rearward loading causes the pickuptruck's rear tires to act as a fulcrum (a teeter totter) responsivelycausing the pickup truck's front tires to have less downward force andtherefore less stability.

One type of cargo commonly carried within a pickup truck bed that causesthis problem is truck campers. Truck campers may have a wide variety ofconfigurations, but are typically somewhat boxlike structures thatdefine an interior living space which may include beds, bathrooms,appliances, and the like. Truck campers provide a popular means ofcombining outdoor recreation while maintaining certain “comforts ofhome” and are becoming increasingly popular. Typically, larger andheavier truck campers are more opulent and therefore more popular. Apickup truck must be able to support the size and weight of the truckcamper within the truck bed, and the carriage of the truck camper withinthe truck bed must not significantly negatively impact the stability,drivability and maneuverability of the pickup truck.

Unfortunately, a four-door pickup truck having a six-foot bed that ismaneuverable and convenient to use and drive has less ability to carry along and heavy truck camper because the truck bed is shorter.Purchasers, owners and operators are therefore frequently forced tochoose between the pickup truck they desire, and the truck camper theydesire because the characteristics of the pickup truck that make it sodesirable, make it less capable of carrying the larger more opulenttruck campers that are more desirable.

Some pickup truck owners have resorted to carrying “oversize” truckcampers within six-foot cargo beds and have “accepted” the lessenedstability and drivability of the pickup truck when the truck camper iswithin the bed. Unfortunately, oversized truck campers have increasedrisk and decreased safety for the pickup truck operator as well as othercitizens using the roadways. A similar situation develops when a load of8′ or 10′ lumber is carried in a 6 foot pickup truck bed.

What is needed is an apparatus that is easily and releasably attachableto a pickup truck which allows the pickup truck to carry cargo itemsthat extended beyond the pickup truck bed and simultaneously supports ofthe weight of the protruding item and prevents the cargo from decreasingthe stability and maneuverability of the pickup truck.

My weight transferring tow dolly seeks to overcome these and otherdrawbacks to pickup trucks carrying oversize and heavy cargo, includingoversized truck campers, by providing a weight transferring tow dollythat is releasably attachable to a trailer hitch of a pickup truck, thatsupports cargo items extending rearwardly from the pickup truck andprevents the center of gravity of the pickup truck from movingrearwardly due to the weight of the cargo within the pickup truck bed.

My invention does not reside in any single one of the identifiedfeatures individually but rather in the synergistic combination of allof its structures, which give rise to the functions necessarily flowingtherefrom as hereinafter claimed.

Some or all of the problems explained above, and other problems, may behelped or solved by my invention shown and described herein. Myinvention may also be used to address other problems not set out hereinor which become apparent at a later time. The future may also bring tolight unknown benefits which may be in the future appreciated from thenovel invention shown and described herein.

SUMMARY

Our weight transferring tow dolly is releasably attachable to a receiverhitch of a towing vehicle such as a pickup truck and generally providesa dolly frame of structurally interconnected box beams, a heightadjustable suspension carrying an axle with wheels and tires at opposingend portions, and a support frame to partially support the weight of aload and to move the center of gravity of a loaded towing vehicleforwardly.

In providing such a weight transferring tow dolly apparatus it is:

a principal object to provide a weight transferring tow dolly thatpartially supports the rearward weight of an over-length load.

a further object to provide a weight transferring tow dolly that movesthe center of gravity of a loaded towing vehicle forwardly.

a further object to provide such a weight transferring tow dolly thatallows a pickup truck to carry an oversize truck camper.

a further object to provide such a weight transferring tow dolly thatmay be towed by a vehicle other than a truck.

a further object to provide such a weight transferring tow dolly thatmaintains the stability of a towing vehicle carrying an over-lengthload.

a further object to provide such a weight transferring tow dolly thatreleasably attaches to a towing vehicle using a standard receiver typetowing hitch.

a further object is to provide such a weight transferring tow dolly thatcarries a towing hitch at a rearward end portion to allow a trailer tobe towed therebehind.

a further object to provide such a weight transferring tow dolly thathas an adjustable suspension.

a further object to provide such a weight transferring tow dolly havinga suspension that incorporates pneumatics to allow the height of theweight transferring tow dolly to be adjustable.

a further object to provide such a weight transferring tow dolly thatuses inflatable airbags to adjust the amount of weight supported by theweight transferring tow dolly.

a further object to provide such a weight transferring tow dolly thatuses pneumatics to force the front tires of a towing vehicle downwardlyagainst the supporting surface to enhance stability.

a still further object to provide such a weight transferring tow dollythat is new and novel in design, of rugged and durable nature, of simpleand economic manufacture and one that is otherwise well suited to theuses and purposes for which it is intended.

Other and further objects of my invention will appear from the followingspecification and accompanying drawings which form a part hereof. Incarrying out the objects of my invention it is to be understood that itsstructures and features are susceptible to change in design andarrangement with only one preferred and practical embodiment of the bestknown mode being illustrated in the accompanying drawings and specifiedas is required.

BRIEF DESCRIPTION OF THE DRAWINGS

Specific forms, configurations, embodiments and/or diagrams relating toand helping to describe preferred versions of the invention areexplained and characterized herein, often with reference to theaccompanying drawings. The drawings and all features shown therein alsoserve as part of the disclosure of the invention whether described intext or merely by graphical disclosure alone. Such drawings are brieflydescribed below.

FIG. 1 is an isometric front, driver's side and top view of the weighttransferring tow dolly.

FIG. 2 is an isometric view back, driver's side and top view thereof.

FIG. 3 is an orthographic driver's side view thereof.

FIG. 4 is an orthographic cross section view thereof taken on line 4-4of FIG. 2.

FIG. 5 is an orthographic plan view thereof.

FIG. 6 is an orthographic front, rearward looking view thereof.

FIG. 7 is an orthographic passenger side view of the weight transferringtow dolly interconnected with a receiver hitch of a towing vehiclepickup truck, shown in dashed outline.

FIG. 8 is an orthographic passenger side view, similar to that of FIG.7, showing a tailgate of the towing vehicle pickup truck (shown indashed outline) lowered to a horizontal (open) position to the samevertical height as the support frame and a truck camper (shown in dashedoutline) carried within the pickup truck bed.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Introductory Notes

The readers of this document should understand that the embodimentsdescribed herein may rely on terminology used in any section of thisdocument and other terms readily apparent from the drawings and thelanguage common therefore as may be known in a particular art and suchas known or indicated and provided by dictionaries. Widely known andused in the preparation hereof are Webster's Third New InternationalDictionary (© 1993), The Oxford English Dictionary (Second Edition,©1989), The New Century Dictionary (©2001-2005) and the AmericanHeritage Dictionary of the English Language (4th Edition ©2000) all ofwhich are hereby incorporated by reference for interpretation of termsused herein and to more adequately or aptly describe various features,aspects and concepts shown or otherwise described herein using moreappropriate words having meanings applicable to such features, aspectsand concepts.

This document is premised upon using one or more terms for featuresshown in one embodiment that may also apply to or be combined with otherembodiments for similar structures, functions, features and aspects ofthe invention. Wording used in the claims is also descriptive of theinvention and the text of both the claims and the abstract areincorporated by reference into the description entirely.

The readers of this document should further understand that theembodiments described herein may rely on terminology and features usedin any section or embodiment shown in this document and other termsreadily apparent from the drawings and language common or propertherefore.

As used herein, the term “forward”, its derivatives, and grammaticalequivalents refers to the portion of my weight transferring tow dollythat is closest to a towing vehicle. The term “rearward”, itsderivatives, and grammatical equivalents refers to the portion of myweight transferring tow dolly most distant from the towing vehicle. Theterm “outer”, its derivatives, and grammatical equivalents refers to thedriver's side or passenger side of my weight transferring tow dolly asopposed to a laterally medial portion of my weight transferring towdolly.

My weight transferring tow dolly 9 generally provides a dolly frame 11having a suspension 16 with an axle 10 and a support frame 51 and isreleasably attachable to a receiver type towing hitch 72 carried at arearward end portion of a towing vehicle 70 which may be a pickup truck.

The dolly frame 11 is formed of a first forward transverse frame beam36, a second medial transverse frame beam 37, and a third rearwardtransverse frame beam 38. Each transverse frame beam 36, 37, 38 has twoopposing end portions 36 a, 36 b, 37 a, 37 b, 38 a, 38 b respectivelywhich structurally communicate with fender mounting beams 34. Thetransverse frame beams 36, 37, 38 are preferably box beams and aregenerally equally spaced apart from one another from front to rear andextend generally horizontally relative to supporting ground surface 74.

A tow beam 30, which is preferably a box beam, extends perpendicularlyto the transverse frame beams 36, 37, 38 and is positioned generallymedially between the opposing end portions 36 a, 36 b, 37 a, 37 b, 38 a,38 b. The tow beam 30 has a forward end portion 30 a, a rearward endportion 30 b, a top surface 30 c and a bottom surface 30 d. The bottomsurface 30 d of the tow beam 30 structurally communicates with a topsurface of the first forward transverse beam 36 and gussets 27 provideadditional strength to the interconnection. The top surface 30 c of thetow beam 30 structurally communicates with bottom surface of the secondmedial transverse frame beam 37 and gussets 27 provide additionalstrength to the interconnection. A receiver hitch insert 20 isstructurally carried at the forward end portion 30 a and is axiallyaligned therewith. The receiver hitch insert 20 has a squarecross-section (not shown) and is preferably formed of a section of asolid beam. The receiver hitch insert 20 may be releasablyinterconnected to the towing hitch 72 of the towing vehicle 70 and thesquare configuration of the receiver hitch insert 20 slidably axiallyengages with a box beam channel (not shown) defined by the towing hitch72. The square cross-section (not shown) of the receiver hitch insert 20and the box beam channel (not shown) defined by the towing hitch 72prevent any lateral vertical and rotational movement between thereceiver hitch insert 20 and the towing hitch 72.

The rearward end portion 30 b of the tow beam 30 extends rearwardly ofthe third transverse frame beam 38 and structurally carries box beamreceiver hitch 22 at the rearward end portion 30 b. The box beamreceiver hitch 22 defines a rectilinear medial channel (not shown)configured to axially slidably removably carry a receiver hitch stinger25 which preferably carries at least one hitch ball 26, to which atrailer hitch (not shown) of a trailer (not shown) may releasably engagein order to tow a trailer (not shown) behind the weight transferring towdolly 9.

As shown in FIG. 4, the first forward transverse frame beam 36 isclosest to the ground surface 74, the second medial transverse framebeam 37 is slightly vertically higher than the first transverse framebeam 36, and the third transverse frame beam 38, which structurallycommunicates with support leg 61 at a generally medial lateral positionis vertically higher than both the first transverse frame beam 36 andthe second transverse frame beam 37.

Fender mounting beams 34 structurally carried at the opposing lateralend portions 36 a, 36 b, 37 a, 37 b, 38 a, 38 b of the transverse framebeams 36, 37, 38 are angulated upwardly toward the rearward end of thetow dolly 9. The rearward upward angulation of the fender mounting beams34 allows the fender mounting beam to simultaneously structurallyinterconnect with all these transverse frame beams 36, 37, 38 andaccommodates the differing vertical heights of the transverse framebeams 36, 37 and 38 and provides rigidity and strength to the dollyframe 11.

Fenders 14 are carried by the fender mounting beams 34 laterallyoutwardly thereof to substantially surround foreword, upper and rearwardportions of tires 13 in order to prevent the tires 13 from “casting off”debris, such as rock, sand and gravel that might cause damage tovehicles and persons. In the preferred embodiment, the fenders 14 arestructurally attached to the fender mounting beams 34 by fender brackets35 that extend therebetween and space the fenders 14 laterally outwardlyfrom the dolly frame 11. The configuration of the fenders 14 and thelateral spacing of the fenders 14 away from the dolly frame 11 may bealtered and adjusted during manufacture to accommodate the tires 13 andwheels 12 carried by the axle 10.

Axle 10 carries a rotatable wheel hub (not shown) at each opposing endportion and a wheel 12 carrying a tire 13 is fastened to each wheel hub(not shown) using known threaded wheel studs (not shown) and lug nuts.The wheel hubs (not shown) allow the wheels 12 and tires 13 to rotateindependent of one another.

The suspension 16 interconnects the dolly frame 11 and the axle 10 andhas similar components at each lateral side portion of the dolly frame11. The suspension 16 has swing arms 17, swing arm brackets 19, swingarm axles 18 and in the preferred embodiment air bags 41. A pair ofspaced apart swing arm brackets 19 are structurally interconnected to abottom surface of the forward transverse frame beam 36 proximate eachlateral end portion 36 a, 36 b and extended downwardly therefrom. Theswing arm brackets 19 define a medial hole (not shown) proximate an endportion opposite the first transverse frame beam 36 to carry a swing armaxle 18 extending therethrough to pivotally attach the swing arm 17 tothe swing arm brackets 19. The swing arms 17 are preferably formed ofsections of box beam and each swing arm 17 has a forward end portion 17a and an opposing rearward end portion 17 b. A swing arm axle hole (notshown) is defined in the forward end portion 17 a of each swing arm 17to journal the swing arm axle 18.

In the preferred embodiment the axle 10 is secured to the swing arms 17proximate the rearward end portions 17 b thereof with U-bolts 40 thatsimultaneously extend over and about the axle 10 and the swing arm 17,and engage with a U-bolt bracket (not shown). Threaded nuts are used tosecure the U-bolt brackets to the U-bolts 40, responsively securing theaxle 10 to the swing arms 17. In an alternative embodiment it iscontemplated the axle 10 may be structurally attached to the swing arm17 such as by welding. The length of the swing arms 17 between theforward end portion 17 a where the swing arm axle 18 is carried and therearward end portion 17 b provides mechanical leverage to the swing arms17 which allows significant upward vertical force to be exerted on thedolly frame 11 as the rearward end portions 17 b of the swing arms 17pivot downwardly away from the dolly frame 11.

A sway bar 32 communicates between the axle 10 and the dolly frame 11and is attached to the axle 10 and the dolly frame 11 with sway barbrackets 33. The sway bar 32 dampens vibration and lateral motion of theaxle 10 relative to the dolly frame 11 and adds stability when the towdolly 9 is being towed.

Air bags 41 are positioned between an upper surface of each swing arm 17proximate the rearward end portion 17 b opposite the swing arm axle 18,and a bottom surface of the second medial transverse frame beam 37. Theair bags 41 are positionally secured to the upper surface of each swingarm 17 and the bottom surface of the second medial transverse frame beam37 with air bag mounting brackets 42. The position of the air bags 41relative to the swing arm axles 18 and the pivotal interconnection ofthe swing arms 17 to the dolly frame 11 allow the swing arms 17 to pivotrelative to the dolly frame 11 when the airbags 41 expand and contractresponsive to inflation and deflation.

In the preferred embodiment an air pump (not shown) and relatedelectronics (not shown) are carried in a moisture proof and dust proofcontainer 29, that is carried by the dolly frame 11 at a convenientlocation. Pneumatic lines (not shown) communicate between the air pump(not shown) and the airbags 41 allowing the airbags 41 to be inflatedand deflated as desired. In the preferred embodiment the airbags 41 andpneumatic lines (not shown) are interconnected “in series” so that eachairbag 41 has an equal amount of air pressure and inflation anddeflation of both airbags 41 may be accomplished simultaneously andequally. Inflation of the airbags 41 is accomplished by addingpressurized air into the airbags 41 which causes the airbags 41 toexpand generally axially and responsively pivot the rearward endportions 17 b of the swing arms 17 away from a bottom portion of the towdolly frame 11. Because the swing arms 17 are connected to the axle 10and the wheels 12 and tires 13 carried by the axle 10 are in contactwith the ground surface 74, the pivoting of the swing arms 17 responsiveto the airbag 41 inflation causes the dolly frame 11 to move upwardly.The pneumatic lines (not shown) may also communicate with an airpressure gauge 31 a preferably carried within a pressure gauge housing31 so that a user may monitor the air pressure without the airbags andpneumatic components. In the preferred embodiment, the air pressuregauge housing 31 is carried on a bottom surface of the third transverseframe beam 37 and is visible to an operator from a rearward portion ofthe tow dolly 9. (FIG. 2). An air pressure drain valve (not shown) isalso preferably carried within or proximate the pressure gauge housing31 to allow an operator to drain air pressure from the pneumatic system.

In another embodiment (not shown) air shocks (not shown) may be usedinstead of air bags 41. The air shocks (not shown) communicate betweenthe dolly frame 11 and the rearward end portions 17 b of the swing arms17 opposite the swing arm axles 18. Similarly, when pressurized air isadded to the air shocks (not shown) the air shocks (not shown) expandaxially increasing in length. The increase in the length of the airshocks (not shown) will similarly cause the rearward end portions 17 bof the swing arms 17 to pivot away from the dolly frame 11 andresponsively cause the dolly frame 11 to move upwardly increasing theheight of the dolly frame 11 relative to the ground surface.

In a further embodiment (not shown), it is anticipated a one waypressurized air input valve (not shown) may be used in place of or inaddition to the air pump (not shown). The one way pressurized air inputvalve (not shown) would pneumatically communicate with the air bags 41or air shocks (not shown) and allow pressurized air to be added from anexternal source of pressurized air such as an air compressor at aservice station. It is anticipated use of such a one way pressurized airinput valve would reduce complexity and cost of the tow dolly 9 andwould reduce maintenance. The one way pressurized air input valve isanticipated to be a valve similar to an air valve or an automotivetire/wheel which allows input of pressurized air as well as release ofpressure from within the pneumatic system.

The support frame 51 is formed of a box beams and is carried spacedlyvertically above the dolly frame 11 proximate the rearward end portionand extends generally parallel to the axle 10. The support frame 51 hasan elongate first transverse beam 52 and an elongate second transversebeam 53. The first transverse beam 52 and the second transverse beam 53are structurally interconnected to one another by plural spacer beams54, 55, 56, 57, 58 that are perpendicular thereto and extendtherebetween forming a generally planer “ladder” type structure whereinthe plural spacer beams 54, 55, 56, 57, 58 form the “rungs” of the“ladder” type structure. Spaces 59 are defined between the spacer beams54, 55, 56, 57, 58 and the first and second transverse beams 52, 53.

Support legs 60 and 62 are vertical box beams and structurallycommunicate between an upper surface of the third transverse frame beam38 spacedly adjacent the lateral end portions 36 a and 36 b thereof anda bottom surface of the support frame 51 second transverse beam 53. Thesupport legs 60 and 62 are generally equally laterally spaced apart fromthe fender mounting beams 34 to distribute loads on the support frame 51to the dolly frame 11. Support leg 61 is centrally positioned betweensupport legs 60 and 62 and is preferably formed of a larger size boxbeam than support legs 60 and 62. Support leg 61 structurallycommunicates between a bottom surface of the support frame 51 secondtransverse beam 53 and the top surface 30 c of the tow beam 30. As shownin FIGS. 1 and 2 the third transverse frame beam 38 structurallycommunicates with support leg 61. The structural interconnectiontherebetween preferably requires the third transverse frame beam 38 becut into halves at a generally medial position, and the “cut ends” (notshown) be welded or otherwise permanently affixed to lateral sideportions of support leg 61 spacedly above the tow beam 30. Thestructural interconnection of the third transverse frame beam 38 withsupport leg 61 provides additional lateral stability to the support leg61 and the support frame 51. Forward angulated support 63 is a box beamand structurally communicates between upper surface 30 c of the tow beam30 proximate the forward end portion 30 a, and a forward facing upperend portion 61 a of support leg 61. Rear angulated support beam 64structurally communicates between a rearward facing upper end portion 61a of support leg 61 and an upper surface of the receiver hitch 22carried at the rearward end portion 30 b of the tow beam 30. The forwardangulated support 63 and the rear angulated support 62 provide forwardand rearward rigidity to the support frame 51.

Fastener brackets 65 are structurally carried by the support frame 51 atopposing lateral end portions proximate the second transverse beam 53.The fastener brackets 65 define medial holes 66 for releasableengagement with fasteners that may extend to a truck camper 73 or asupported load.

Vehicle safety features such as, but not limited to, tail lights 15,safety chain loops 24, back-up lights (not shown) and the like may becarried by the tow dolly 9 as desired by the user to satisfy road safetyregulations, and to accommodate the towing of another vehicle behind thetow dolly 9.

Having described the structure of my weight transferring tow dolly, itsassembly and operation may be understood.

Assuming the tow dolly 9 is to be used in conjunction with a pickuptruck carrying a truck camper 73, the truck camper 73 is first loadedinto the truck bed and is secured therein by known means.

The weight transferring tow dolly 9 is positioned behind the towingvehicle 70 with the receiver hitch insert 20 axially aligned with thetowing vehicle 70 towing hitch 72. If the vertical height of the supportframe 51 of the weight transferring tow dolly 9 is too great to passunder a rearward end portion of the truck camper 73 the airbags 41should be deflated so that the swing arms 17 pivot about the swing armaxles 18 and the height of the support frame 51 relative to the groundsurface 74 is reduced so that the weight transferring tow dolly 9 maypass under the truck camper 73 the air bags 41 are deflated by operatingthe air pressure drain valve (not shown). Forward end portion of thereceiver hitch insert 20 is inserted axially into the box beam medialchannel (not shown) defined by the towing hitch 72 and locking pin holes21 defined therein are aligned. A locking pin (not shown) is insertedthrough the aligned locking pin holes 21 and secured in place with knownmeans such as a Kotter-Pin to secure the receiver hitch insert 20 withinthe towing hitch 72. The square cross-section configuration of thereceiver hitch insert 20 and the box beam medial channel (not shown) ofthe towing hitch 72 cooperate with the locking pin (not shown) toprevent vertical, lateral, rotational or axial movement of the receiverhitch insert 20 relative to the towing hitch 72. Electrical connections(not shown) operatively communicating between the towing vehicle 70 andthe weight transferring tow dolly 9 to power the tall lights 15, airpump (not shown) and other features such as back-up lights (not shown)are connected.

The air pump (not shown) which may electrically communicate with anelectrical power system (not shown) of the towing vehicle 70, or haveindependent battery power, is activated which causes the air pump (notshown) to force pressurized air through pneumatic lines (not shown) andinto the air bags 41. As pressurized air passes into the air bags 41,the airbags 41 expand axially causing the swing arms 17 to pivot aboutthe swing arm axles 18. As the air bags 41 expand and the rearward endportions 17 b of the swing arms 17 pivot away from the dolly frame 11,the vertical height of the dolly frame 11 and the support frame 51relative to the ground surface (not shown) increases until an uppersurface of the support frame 51 frictionally contacts a bottom surface(not shown) of the truck camper 73. As pressurized air continues toexpand the air bags 41, the rearward end portions 17 b of the swing arms17 continue to pivot away from the dolly frame 11, and additional upwardvertical pressure is exerted on the bottom surface (not shown) of thetruck camper 73 proximate the rearward end portion of the truck camper73. As vertical upward pressure is exerted on the bottom of the truckcamper 73 proximate a rearward end portion thereof, the rear wheels ofthe towing vehicle 70 become pivot points (fulcrums) which causesadditional vertical downward pressure to be exerted on the front wheelsand tires (not shown) of the towing vehicle 70 which increases thestability of the towing vehicle 70. The weight of the truck camper 73that is carried behind the rear wheels of the towing vehicle 70 isthereby partially supported by the tow dolly 9 and the upward pressureexerted by the tow dolly 9 on the bottom surface of the truck camper 73forces the towing vehicles 70 front wheels and tires downwardly toenhance stability. Similarly the generally rigid interconnection of thetow dolly 9 with the towing vehicle 70 of the towing hitch 72 causes theweight of the load on the rear wheels of the towing vehicle to be atleast partially shared with the wheels 12 and tires 13 of the tow dolly9.

The process of detaching the weight transferring tow dolly 9 from thetowing vehicle 70 is generally the reverse of the attaching processdescribed in detail above and would be initiated by releasing the airpressure from the airbags and pneumatic components by opening the airpressure drain valve (not shown).

Construction and Materials of the Apparatus

The tow dolly frame 11, support frame 11 and related components arepreferably formed of steel box beams that are welded to another toprovide structural interconnections therebetween. In the preferredembodiment the dolly frame 11, support frame 11 and related componentsare finished with a powder coating to provide an attractive yet durableand wear resistant finish. The axle 10, wheels 12 and tires 13 arecommercially available in a wide variety of sizes to satisfy therequirements of nearly any user. The air pump (not shown) pneumaticlines (not shown) and airbags 41 or air shocks (not shown) are alsocommercially available. The operating air pressure of the pneumaticsystem is dependent upon the desires of the operator, the weight andlength of the load being carried in the truck bed (not shown) and thelength and weight of the towing vehicle 70. In the preferred embodimentthe tow dolly 9 and its various components are formed of steel boxbeams, however it is contemplated aluminum and various other metallicalloys may likewise be used in the manufacturing of the tow dolly 9.

INTERPRETATION NOTES

The above description has set out various features, functions, methodsand other aspects of the invention. This has been done with regard tothe currently preferred embodiments thereof. Time and furtherdevelopment may change the manner in which the various aspects areimplemented. Such aspects may further be added to by the language of theclaims which are incorporated by reference hereinto as originally filed.The scope of protection accorded the invention, as defined by theclaims, is not intended to be necessarily limited to the specific sizes,shapes, features or other aspects of the currently preferred embodimentshown and described. The claimed invention may be implemented orembodied in other forms still being within the concepts shown, describedand claimed herein. Also included are equivalents of the invention whichcan be made without departing from the scope or concepts properlyprotected hereby.

The foregoing description of my invention is necessarily of a detailednature so that a specific embodiment of a best mode may be set forth asis required, but it is to be understood that various modifications ofdetails, sizes, and rearrangement, substitution and multiplication ofthe parts may be resorted to without departing from its spirit, essenceor scope.

Having thusly described my invention, the preferred embodiment and itsuse, what I desire to protect by Utility Letters Patent, and

What I claim is:
 1. A tow dolly releasably attached to and towablebehind a towing vehicle having at a rearward end portion a receiver typetowing hitch defining a rearwardly opening box beam channel, the towdolly comprising in combination: a dolly frame having plural spacedapart transverse frame beams and a tow beam having a forward end portioncarrying a receiver hitch insert for releasable engagement with thereceiver type towing hitch of the towing vehicle; an axle having wheelsand tires at each opposing end portion to support the dolly framespacedly above a supporting surface; a suspension interconnecting thedolly frame and the axle, the suspension having, a swing arm with aforward end portion and a rearward end portion, the forward end portionpivotally interconnected to the dolly frame so that the rearward endportion may pivot towards the dolly frame and away from the dolly frame,connecting means positionally securing the axle to the swing armspacedly adjacent the rearward end portion, a pneumatic apparatuscommunicating between the dolly frame and the swing arm to pivot theswing arm relative to the dolly frame responsive to axial expansion andcontraction of the pneumatic apparatus, and pneumatic linescommunicating with the pneumatic apparatus and a pneumatic valve tosupply pressurized air to the pneumatic apparatus and to drainpressurized air from the pneumatic apparatus; a support frame carriedspacedly above the dolly frame that is vertically adjustablypositionable responsive to the axial expansion and contraction of thepneumatic apparatus.
 2. The tow dolly of claim 1 further comprising: anair pump communicating with the pneumatic lines and pneumatic apparatusto supply pressurized air to the pneumatic apparatus.
 3. The tow dollyof claim 1 further comprising: a receiver hitch at a rearward endportion of the tow beam opposite the receiver hitch insert to carry areceiver hitch stinger carrying a hitch ball to allow a trailer to beinterconnected therewith and towed behind the tow dolly.
 4. The twodolly of claim 1 wherein: the pneumatic apparatus is an airbag.
 5. Thetow dolly of claim 1 wherein: the pneumatic apparatus is an air shock.6. The tow dolly of claim 1 wherein: the receiver hitch insert has asquare cross section configuration and engagement of the receiver hitchinsert with the box beam channel defined by the towing hitch preventsvertical, lateral, axial and rotational movement therebetween; and axialexpansion of the pneumatic apparatus responsive to addition ofpressurized air thereto causes the tow dolly to exert upward force on arearward end portion of the towing vehicle by forcing the tow dolly axledownwardly.